Support is requested to partially fund a Symposium which will address host bacteria interactions of importance in periodontal diseases. The symposium is planned for Sept. 24-26, 1980 in Niagara Falls, New York. A total of 40 to 50 speakers and moderators, each expert in his or her field, will be asked to participate. The speakers will be requested to present a timely overview and new data on an assigned topic in their area of expertise. They will also be requested to submit a written manuscript, and these will form the basis for publication of the Proceedings of the Symposium. Poster sessions are planned to be open to those who wish to present new data. This will represent the first Symposium specifically addressing host parasite interactions occurring in periodontal diseases. It will attempt to provide for dissemination of information and ideas to an extent not achievable by conventional means of communication, such as publication and more formal scientific meetings. In addition, it is hoped that scientists whose main interests are either microbiology, immunology or clinical periodontology bring each other up-to-date on the latest developments, and will analyze these developments, suggesting new approaches for the study of periodontal diseases and other similar chronic bacterial infections. Such a Symposium is timely because of the recent advances made in enumeration of potentially periodontopathic microflora and in elucidation of destructive and protective host responses operating in periodontal diseases. Meaningful study of host responses are best made after recognition of the potential pathogens. On the other hand, study of immune responses may very well reveal which are the important pathogens once a series of potential causative organisms are recognized. Hence since knowledge is rapidly advancing in both microbiology and immunology of periodontal disease, the Symposium will likely serve to facilitate collaboration among active researchers, and cooperation among institutions engaged in clinical and basic research in periodontal diseases.